This invention relates to a two-component adhesive or sealing composition, the first component comprising an epoxy resin and an isocyanate pre-polymer with ether and blocked urethane groups, and the second component comprising a suitable amine hardener, a tertiary amine primary accelerator and a mercaptan terminated polymer as a secondary accelerator, such as Capcure 3-800.
Many adhesive compositions, based on epoxy reins, are known. These compositions generally are two-component compositions, the first component including the epoxy resin and the second component including a hardener for the epoxy resin. When the two components are blended together, the epoxy resin hardens and sets. Capcure 3-800 made by Diamond Shamrock Corporation, is an accelerator or hardener which is known to impart rapid cure characteristics to epoxy reins, in combination with selected amines. However, Capcure 3-800 is generally not known as a hardener or accelerator for any other type of resin system, such as the resin system of the invention. European Patent Application No. 0 024 501 in the name of Teroson GmbH discloses a two-component polyurethane sealing composition for use in sealing glass into window frames and the like. The first component of this composition comprises 10 to 50 percent by weight of linear or branched polymers with ether and urethane groups as well as cross-linkable blocked isocyanate groups, 0 to 15 percent by weight of epoxy resin, 0.1 to 2.5 percent by weight of trialkoxy silane, 2 to 25 percent by weight of plasticiser and optionally 0.5 to 5 percent by weight of a thixotropic agent.
The first component is stated to contain 0 to 15 percent by weight of epoxy resin. However, the first component also contains various non-reactive plasticisers and fillers. Adjusting the percentage of epoxy resin so that the percentage is based solely on the percentage of the polymer with ether and urethane groups and blocked isocyanate groups in the first component, the maximum percentage of epoxy resin disclosed in the specification in Example 6, is 33 percent by weight of the total weight of the epoxy resin and the polymer.
The second component of this sealing composition contains a cycloaliphatic diamine as a hardener and a tertiary amine or amine derivative as an accelerator. Further, in the specification it is stated that it is advantageous to add to the second component a low viscosity polymercaptan resin such as Capcure 3-800 in quantities of about 5 to 20 percent by weight related to the second component. It is stated that this additive has two advantages. It increases the mechanical strength of the overall compound and makes it more viscoplastic when it has hardened. There are no examples in the patent application which illustrate the use of Capcure 3-800. The amount of Capsure 3-800 specified in this patent application is outside the range of amounts of the mercaptan terminated polymer which is used in the second component of the composition of the present invention.